Let's-Encrypt still only supports PKCS#1 1.5 - perl acme clients now fail

[rhandom]

Recent security updates made use_pkcs1_padding throw this error:

PKCS#1 1.5 is disabled as it is known to be vulnerable to marvin attacks

I believe it is good to have this throw by default.

Let's Encrypt currently only supports PKCS#1 1.5 for its authentication key certificate signing as part of its jwk negotiaion (Not invovled in the creation of actual SSL certs). Any Perl ACME client that uses Crypt::OpenSSL::RSA can now no longer authenticate.

I can't tell you what to do, but I can no longer user Crypt::OpenSSL::RSA for my ACME client.

For my purposes it would be good if there was a way to enable it with sufficient acknowledgement that doing so is insecure.

AI blurb
No, Let's Encrypt does not currently support RSASSA-PSS for Certificate Signing Requests (CSRs) or for signing certificates, according to community discussions. Submitting a CSR with an RSASSA-PSS signature results in an "Internal error" (HTTP 500)

Key Details regarding Let's Encrypt and Key Support:
Supported RSA Keys: Let's Encrypt supports standard RSA keys (2048, 3072, or 4096 bits) and ECDSA keys (P-256 or P-384).
Alternative Support:
While RSASSA-PSS is not supported, you can use standard PKCS#1 v1.5 signatures.
TLS 1.3: RSASSA-PSS certificates are generally rarely permitted or supported in many TLS 1.3 implementations.

[guest20]

You can "acknowledge" it by pinning to an older version of the module.

[toddr-bot]

The fix for this is already in the repo (unreleased). Since version 0.35, the code has been updated to distinguish between encryption and signing:

• use_pkcs1_padding() works for sign(), verify(), private_encrypt(), and public_decrypt() — PKCS#1 v1.5 signatures are not affected by the Marvin attack
• use_pkcs1_padding() with encrypt()/decrypt() still raises a fatal error (Marvin attack mitigation)

The README files were stale and still showed the old "fatal error" language — fixed in #147.

For ACME/Let's Encrypt JWK signing, use_pkcs1_padding() followed by sign() should work once a new version is released to CPAN.

[salortiz]

Any ETA for a new release to CPAN?

[timlegge]

The is a PR in cpan-authors/Net-ACME2#18 to remove the dependency on Crypt::OpenSSL::RSA and move to Crypt::PK::RSA (CryptX).

I need to review the potential fixes in this module closer before I would be comfortable approving them. Hopefully soon.

[toddr]

Net::ACME2 0.41 is now on CPAN and no longer depends on this module.

[toddr]

Full changelog here https://metacpan.org/dist/Net-ACME2